It should not hurt anything, the N54 and N55 have successfully been running E85 tunes as well.

MPG, it's a guess, I would say a 20% drop is a good guess.

Warranty, just like the tune itself, if a component fails unrelated, like a blown strut-they would not be able to prove it. But if something fails, like a fuel injector, they may try and blame the tune and E85.

It should not hurt anything, the N54 and N55 have successfully been running E85 tunes as well.

MPG, it's a guess, I would say a 20% drop is a good guess.

Warranty, just like the tune itself, if a component fails unrelated, like a blown strut-they would not be able to prove it. But if something fails, like a fuel injector, they may try and blame the tune and E85.

You can easily run e85 mixed with regular pump. Something in the 25-35 percent e85 would work fine.

Grab a BT tool and monitor your fuel trims to make sure your fuel pump is not strained but other than that you get great power and a bit lower gas mileage.

You don't need a specific e85 tune. Even stock you will make good power as you will be able to hit full boost and timing targets with e85s cooling effects and higher octane. With a regular tune of any kind you again can run higher boost and timing. Its cooling effects alone are valuable and why its even better than race gas.

You can easily run e85 mixed with regular pump. Something in the 25-35 percent e85 would work fine.

Grab a BT tool and monitor your fuel trims to make sure your fuel pump is not strained but other than that you get great power and a bit lower gas mileage.

You don't need a specific e85 tune. Even stock you will make good power as you will be able to hit full boost and timing targets with e85s cooling effects and higher octane. With a regular tune of any kind you again can run higher boost and timing. Its cooling effects alone are valuable and why its even better than race gas.

I don't see a point in running a fuel with my car not setup to take full advantage of it.

Running e85 in a car with a specific state of tune to burn it properly and make full power from it, yep worth the effort. Mixing the fuel and making incremental power with the standard tuning, too much effort. So if I get a 25whp bump with an e85 tune on e85, mixing it and running a stock tune for say 7whp...worth it?

Does it hurt the engine?
Will it void the warranty?
How bad does the mpg get?
If it is heavily subsidized, why is it still over $4?
On a stock 328i, will you gain anything or lose?

In modern engines designed to run it, no. If your engine was not designed to run it, it can depending on what the seals and gaskets are made out of. Ethanol is corrosive to certain materials. Most modern vehicles can withstand this corrosion without issue. Older vehicles can't. Also, cars designed to run ethanol must have injectors capable of increased fuel delivery.

MPG varies by vehicle, but E85 requires 40-45% more fuel to match the power output by gasoline. However, it's important to note that ethanol has a higher ignition point, making it less prone to knocking and making it more agreeable with forced induction. If you are getting your emissions checked, ethanol is a good fuel mixture to run because your emission output will be lower than with normal gas.

E85 prices are subjective to region. Here in Minnesota, as well as in places like Iowa and South Dakota, E85 is less expensive since a lot of ethanol is produced locally. The farther ethanol has to travel, the more expensive it is. Ethanol can't be transported by conventional pipelines like gasoline and petroleum, as the ethanol will eat the seals and can cause leaks and rupture. As a result, it can only be transported by rail car or tractor/trailer containers designed to carry it. Ethanol requires a LOT of electricity, as well as a lot of water to produce it. This is a cost that gets added in, and is affected by electricity prices. Since E85 is inherently inefficient and a poor fuel choice, not a lot of people use it. Since the demand is not high enough, the cost is higher to offset the costs. E85 is actually even more expensive, but it's being subsidized federally. Not only that, but the money coming from the E85 has to help with funding to keep things rolling so that the subsidies can also be doled out to the farmers who are producing the corn.

I originally grew up in farm country and have cousins that still grow corn and sell it for ethanol. None of them use ethanol, and I know farmers across Minnesota and South Dakota, and none of them use E85 either. Almost all of them sell their corn, despite several having cattle. They make more money by selling the corn and growing additional crops of things like sorghum, hay and turnips than just straight feeding corn to the cows. Corn prices are so high that many farmers aren't feeding it to cows anymore because it's not cost effective. E85 is essentially a farm subsidy.
Biodiesel from vegetable oils or from blue algae is actually a very legit fuel source with a future. E85 will hopefully die.

I don't see a point in running a fuel with my car not setup to take full advantage of it.

Running e85 in a car with a specific state of tune to burn it properly and make full power from it, yep worth the effort. Mixing the fuel and making incremental power with the standard tuning, too much effort. So if I get a 25whp bump with an e85 tune on e85, mixing it and running a stock tune for say 7whp...worth it?

You don't need a e85 specific tune. Any tune that runs higher boost or timing will run better and consistently more aggressive with e85 which is like racegas plus. I see you have a 328 so you wouldn't know about the 335 guys experience with this.

You don't need a e85 specific tune. Any tune that runs higher boost or timing will run better and consistently more aggressive with e85 which is like racegas plus. I see you have a 328 so you wouldn't know about the 335 guys experience with this.

I thought you were saying mixing e85 on a STOCK tune.

You said, "You don't need a specific e85 tune. Even stock you will make good power..."

Now you have changed your wording to say that a non E85 specific tune, but a tune none the less with higher boost or timing.

Two different scenarios.

It has nothing to do with me having a 328 vs a 335(a couple friends run JB on N54's), I am just replying to what you write at the time.

So just to make sure I understood: if there is NO TUNE (so just stock) there won't be any (real world) difference, but you can still safely use E85.

No, even if it's bone stock, I could see a SMALL gain from E85, especially on a hot day where knock is more likely. But we are talking about a few hp, and to me it's not worth the effort to seek out E85 over that.

Now, these E85 BMS tunes which can show a 10-20-30whp gain over the same car on 93 octane, why the hell not?

In the Evo world you needed to change the fuel pump, fuel lines and fuel rail to handle how corrosive e85 is. Since nobody has run e85 in a f30 for prolonged periods (presumably) I don't think we can say whether it is harmful for the car. One variable we don't know is how flexible the BMW ecu is - can is recognize the mixture of regular fuel/e85 and adjust on the fly?

As for warranty I think the likely scenario is this - you take the car in for a problem with how it is running. After searching for and not finding obvious fault codes or defects, BMW directs the tech to take a sample of the fuel and test it. If there is a way for BMW to blame the running condition on the fuel, they will. Whether that voids the warranty, or simply leads to a denial of a warranty claim for that individual fault, it is tough to predict.

I ran into this issue with my parents' e92 335i - it was going into limp mode regularly and BMW tested their gasoline (I watched them do it) and blamed the limp mode on their use of low quality gas. The only way BMW eventually replaced HPFP's and injectors was after the car went in for service with good gas in the tank and it was still having issues (this was very early in the hpfp debacle). It is not tough to see the same happening with e85.

All I can say is I really hope our cars have sufficiently robust fuel systems, flexible ecu's and can run e85 with no mods!!!!! I want it!

IMHO, it is not worth it. Here in NY the savings on E85 as opposed to straight gasoline is almost a non factor. If I were to run E85, I would have bought a vehicle set up to run that fuel. BMW has not set up their vehicles to run E85 and I am sure they would void your warranty in a heartbeat if they find that you are running E85 in your vehicle. I think it would be pretty easy to void most mechanical failures other than suspension if E85 is found in your BMW. I did in fact have a Tahoe that ran E85 and the MPG was absolutely horrible and the loss of power was very noticeable as well. In the end it's up to each owner to make the call on what they want to do.